Color sorters that sort acceptable items and unacceptable items in particulate matter, or that eliminate foreign matter admixed into particulate matter, are widely known in the prior art.
In a color sorter, particulate matter that is launched into the air, for example, from the edge of a chute or belt, is irradiated with light, whereupon the reflected light or transmitted light from the particulate matter is detected by sensors. The detection signal is compared with a reference value to identify unacceptable items or foreign matter, whereupon the unacceptable items or foreign matter are eliminated by being carried away with jets of air from ejector nozzles or the like, thereby sorting the particulate matter (see Patent Documents 1 and 2, for example).
FIG. 13 shows the ejector nozzle of the sorter disclosed in Patent Document 1. The ejector nozzle 101 has a plurality of slit-like air jet holes 102 and a plurality of holes 103 communicating with the air jet holes 102, with hoses 104 that connect to a jet air supply, not shown, fitted into each of the plurality of holes 103 to jet air from the air jet holes 102.
However, a problem with the ejector nozzle 101 in question is that difficulties arise when the hoses 104 dislodge from the holes 103. Moreover, dust and dirt tends to collect in the ejector nozzle 101, including the hoses 104, making frequent cleaning and maintenance necessary.
FIG. 14 shows an air jetting device of the sorter disclosed in Patent Document 2. In the air jetting device 111 in question, a plurality of nozzle blocks 112, a plurality of electromagnetic valves 113 connected in duct-wise fashion to the plurality of nozzle blocks 112, and a single receiver tank 114 connected in duct-wise fashion plurality of electromagnetic valves 113 are arranged on a base 115. In the air jetting device 111 in question, compressed air held in the receiver tank 114 is supplied through ducts to the electromagnetic valves 113, and when a specific electromagnetic valve 113 is opened, air is supplied through a duct to the corresponding nozzle block 112, whereupon air is jetted from a nozzle 116 formed at the tip of the nozzle block 112.
In the air jetting device 111, the nozzle blocks 112 and the electromagnetic valves 113 are respectively connected by ducts, so there is no problem of difficulties arising when the hoses 104 dislodge from the holes 103, as in the aforedescribed ejector nozzle 101.
However, in the air jetting device 111, the plurality of nozzle blocks 112, the plurality of electromagnetic valves 113, and the receiver tank 114 are respectively connected by ducts and arranged on the base 115, making cleaning and maintenance elaborate.